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authorLinus Torvalds <torvalds@linux-foundation.org>2021-05-15 08:28:08 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-05-15 08:28:08 -0700
commit393f42f113b607786207449dc3241d05ec61d5dc (patch)
tree897775bb68ea431d360a1494f9c32b186b3932dd
parent33f85ca44eec7f1ad4be3f3b8d575845b789f1b3 (diff)
parent237388320deffde7c2d65ed8fc9eef670dc979b3 (diff)
Merge tag 'dax-fixes-5.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm
Pull dax fixes from Dan Williams: "A fix for a hang condition due to missed wakeups in the filesystem-dax core when exercised by virtiofs. This bug has been there from the beginning, but the condition has not triggered on other filesystems since they hold a lock over invalidation events" * tag 'dax-fixes-5.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm: dax: Wake up all waiters after invalidating dax entry dax: Add a wakeup mode parameter to put_unlocked_entry() dax: Add an enum for specifying dax wakup mode
-rw-r--r--fs/dax.c35
1 files changed, 23 insertions, 12 deletions
diff --git a/fs/dax.c b/fs/dax.c
index 69216241392f..62352cbcf0f4 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -144,6 +144,16 @@ struct wait_exceptional_entry_queue {
struct exceptional_entry_key key;
};
+/**
+ * enum dax_wake_mode: waitqueue wakeup behaviour
+ * @WAKE_ALL: wake all waiters in the waitqueue
+ * @WAKE_NEXT: wake only the first waiter in the waitqueue
+ */
+enum dax_wake_mode {
+ WAKE_ALL,
+ WAKE_NEXT,
+};
+
static wait_queue_head_t *dax_entry_waitqueue(struct xa_state *xas,
void *entry, struct exceptional_entry_key *key)
{
@@ -182,7 +192,8 @@ static int wake_exceptional_entry_func(wait_queue_entry_t *wait,
* The important information it's conveying is whether the entry at
* this index used to be a PMD entry.
*/
-static void dax_wake_entry(struct xa_state *xas, void *entry, bool wake_all)
+static void dax_wake_entry(struct xa_state *xas, void *entry,
+ enum dax_wake_mode mode)
{
struct exceptional_entry_key key;
wait_queue_head_t *wq;
@@ -196,7 +207,7 @@ static void dax_wake_entry(struct xa_state *xas, void *entry, bool wake_all)
* must be in the waitqueue and the following check will see them.
*/
if (waitqueue_active(wq))
- __wake_up(wq, TASK_NORMAL, wake_all ? 0 : 1, &key);
+ __wake_up(wq, TASK_NORMAL, mode == WAKE_ALL ? 0 : 1, &key);
}
/*
@@ -264,11 +275,11 @@ static void wait_entry_unlocked(struct xa_state *xas, void *entry)
finish_wait(wq, &ewait.wait);
}
-static void put_unlocked_entry(struct xa_state *xas, void *entry)
+static void put_unlocked_entry(struct xa_state *xas, void *entry,
+ enum dax_wake_mode mode)
{
- /* If we were the only waiter woken, wake the next one */
if (entry && !dax_is_conflict(entry))
- dax_wake_entry(xas, entry, false);
+ dax_wake_entry(xas, entry, mode);
}
/*
@@ -286,7 +297,7 @@ static void dax_unlock_entry(struct xa_state *xas, void *entry)
old = xas_store(xas, entry);
xas_unlock_irq(xas);
BUG_ON(!dax_is_locked(old));
- dax_wake_entry(xas, entry, false);
+ dax_wake_entry(xas, entry, WAKE_NEXT);
}
/*
@@ -524,7 +535,7 @@ retry:
dax_disassociate_entry(entry, mapping, false);
xas_store(xas, NULL); /* undo the PMD join */
- dax_wake_entry(xas, entry, true);
+ dax_wake_entry(xas, entry, WAKE_ALL);
mapping->nrpages -= PG_PMD_NR;
entry = NULL;
xas_set(xas, index);
@@ -622,7 +633,7 @@ struct page *dax_layout_busy_page_range(struct address_space *mapping,
entry = get_unlocked_entry(&xas, 0);
if (entry)
page = dax_busy_page(entry);
- put_unlocked_entry(&xas, entry);
+ put_unlocked_entry(&xas, entry, WAKE_NEXT);
if (page)
break;
if (++scanned % XA_CHECK_SCHED)
@@ -664,7 +675,7 @@ static int __dax_invalidate_entry(struct address_space *mapping,
mapping->nrpages -= 1UL << dax_entry_order(entry);
ret = 1;
out:
- put_unlocked_entry(&xas, entry);
+ put_unlocked_entry(&xas, entry, WAKE_ALL);
xas_unlock_irq(&xas);
return ret;
}
@@ -937,13 +948,13 @@ static int dax_writeback_one(struct xa_state *xas, struct dax_device *dax_dev,
xas_lock_irq(xas);
xas_store(xas, entry);
xas_clear_mark(xas, PAGECACHE_TAG_DIRTY);
- dax_wake_entry(xas, entry, false);
+ dax_wake_entry(xas, entry, WAKE_NEXT);
trace_dax_writeback_one(mapping->host, index, count);
return ret;
put_unlocked:
- put_unlocked_entry(xas, entry);
+ put_unlocked_entry(xas, entry, WAKE_NEXT);
return ret;
}
@@ -1684,7 +1695,7 @@ dax_insert_pfn_mkwrite(struct vm_fault *vmf, pfn_t pfn, unsigned int order)
/* Did we race with someone splitting entry or so? */
if (!entry || dax_is_conflict(entry) ||
(order == 0 && !dax_is_pte_entry(entry))) {
- put_unlocked_entry(&xas, entry);
+ put_unlocked_entry(&xas, entry, WAKE_NEXT);
xas_unlock_irq(&xas);
trace_dax_insert_pfn_mkwrite_no_entry(mapping->host, vmf,
VM_FAULT_NOPAGE);

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